In a machine tool of this type, known from German Patent Publication DE 29 35 523 C2, the tool magazine per se is rotatable and is disposed at a location remote from the main spindle. A manipulator is disposed between the main spindle and the transfer position in the magazine, for example in the form of a double arm gripper, which can pick up tools with both ends, i.e. during a tool change it takes the already employed tool off the main spindle with one end and with the other end takes the next tool out of the magazine, performs a turn of, for example, 180.degree. and places the already employed tool into the magazine and places the new next tool on the main spindle. A very rapid tool change is advantageous here, since during processing by the main spindle a search movement of the magazine can be performed in such a way that the needed successive tool is placed into the transfer position while the workpiece is being processed. In addition, the tools here are outside of the machining area, so that as a result no spoiled edges occur. However, the disadvantage here is the construction and therefore monetary outlay, because the double arm gripper must perform at least three movements which are powered electromechanically, hydraulically or in a like manner, namely a gripping and release movement with respect to the tools, a back-and-forth movement directed vertically with respect to the main spindle axis for removing and placing the tools, and a rotating movement for transferring the tools from the main spindle to the magazine and vice versa.
In a further machine tool of this type, known from German Patent Publication DE 33 17 554 C2, the tool magazine can be spread open at a place on the periphery near the main spindle, so that a tool can be moved out of the tool magazine, picked up by the main spindle and again be returned to the tool magazine in this manner. The so-called chip-to-chip time can also be kept short constantly with this known machine tool, since it is possible to move the next tool to be used into the range of the spreadable peripheral location within the tool magazine during processing by a tool.
However, with this type of a so-called pickup system it has been shown that, because of the process of spreading open the tool magazine and the extension out of and retraction into the tool magazine of the holder equipped with or to be equipped with the respective tool, the structural layout of the kinematics for spreading the tool magazine is relatively elaborate and is prone to fail, particularly in case of large magazines and/or heavy tools.
Since industry demands larger and larger magazines and more complex tools, after some prototypes had been built it has been found that spreading magazines of this type are not only too prone to fail, but are also too noisy.